1. Field of the Invention
This invention relates to metal corrosion-inhibited aqueous alcohol solutions, particularly antifreeze compositions useful as coolants in a heat exchange system such as the cooling system of an internal combustion engine.
2. Prior Art
It is conventional to utilize a base such as an alkali metal hydroxide, carbonate, and bicarbonate in an amount sufficient to provide an initial pH of about 8.5 to 10 in an aqueous antifreeze composition as disclosed in U.S. Pat. No. 2,815,328. Conventional coolant compositions tend to drift downward in pH during use as the result of the generation of acidic decomposition products.
It is also known to utilize a hydroxybenzoic acid in an antifreeze as a pH buffer from U.S. Pat. Nos. 4,209,415; 4,209,416; 4,210,547; 4,210,548; 4,210,549; and 4,234,440.
The use of water-soluble carbonates, including bicarbonates not only as buffers but also as a means of raising the pH by decarboxylation of said carbonates at elevated temperatures encountered when the cooling compositions are utilized as heat transfer fluids, is novel.